2015-08-02T20:29:23ZThe comparison of normalization procedures based on different classification systemshttp://hdl.handle.net/10016/21444
The comparison of normalization procedures based on different classification systems
Li, Yunrong; Ruiz-Castillo, Javier
In this paper, we develop a novel methodology within the IDCP measuring framework for comparing normalization procedures based on different classification systems of articles into scientific disciplines. Firstly, we discuss the properties of two rankings, based on a graphical and a numerical approach, for the comparison of any pair of normalization procedures using a single classification system for evaluation purposes. Secondly, when the normalization procedures are based on two different classification systems, we introduce two new rankings following the graphical and the numerical approaches. Each ranking is based on a double test that assesses the two normalization procedures in terms of the two classification systems on which they depend. Thirdly, we also compare the two normalization procedures using a third, independent classification system for evaluation purposes. In the empirical part of the paper we use: (i) a classification system consisting of 219 sub-fields identified with the Web of Science subject-categories; an aggregate classification system consisting of 19 broad fields, as well as a systematic and a random assignment of articles to sub-fields with the aim of maximizing or minimizing differences across sub-fields; (ii) four normalization procedures that use the field or sub-field mean citations of the above four classification systems as normalization factors; and (iii) a large dataset, indexed by Thomson Reuters, in which 4.4 million articles published in 1998–2003 with a five-year citation window are assigned to sub-fields using a fractional approach. The substantive results concerning the comparison of the four normalization procedures indicate that the methodology can be useful in practice.
2013-10-01T00:00:00ZQuantitative evaluation of alternative field normalization procedureshttp://hdl.handle.net/10016/21443
Quantitative evaluation of alternative field normalization procedures
Li, Yunrong; Radicchi, Filippo; Castellano, Claudio; Ruiz-Castillo, Javier
Wide differences in publication and citation practices make impossible the direct comparison
of raw citation counts across scientific disciplines. Recent research has studied new and
traditional normalization procedures aimed at suppressing as much as possible these disproportions
in citation numbers among scientific domains. Using the recently introduced
IDCP (Inequality due to Differences in Citation Practices) method, this paper rigorously tests
the performance of six cited-side normalization procedures based on the Thomson Reuters
classification system consisting of 172 sub-fields. We use six yearly datasets from 1980 to
2004, with widely varying citation windows from the publication year to May 2011. The
main findings are the following three. Firstly, as observed in previous research, within each
year the shapes of sub-field citation distributions are strikingly similar. This paves the way
for several normalization procedures to perform reasonably well in reducing the effect on
citation inequality of differences in citation practices. Secondly, independently ofthe year of
publication and the length of the citation window, the effect of such differences represents
about 13% of total citation inequality. Thirdly, a recently introduced two-parameter normalization
scheme outperforms the other normalization procedures over the entire period,
reducing citation disproportions to a level very close to the minimum achievable given the
data and the classification system. However, the traditional procedure of using sub-field
mean citations as normalization factors yields also good results.
2013-07-01T00:00:00ZTwo perspectives on preferences and structural transformationhttp://hdl.handle.net/10016/21442
Two perspectives on preferences and structural transformation
Herrendorf, Berthold; Rogerson, Richard; Valentinyi, Akos
We assess the empirical importance of changes in income and relative prices for structural transformation in the postwar United States. We explain two natural approaches to the data: sectors may be categories of final expenditure or value added; e.g., the service sector may be the final expenditure on services or the value added from service industries. We estimate preferences for each approach and find that with final expenditure income effects are the dominant force behind structural transformation, whereas with value-added categories price effects are more important. We show how the inputoutput structure of the United States can reconcile these findings.
2013-12-01T00:00:00ZDoes (average) size matter?: Court enforcement, business demography and firm growthhttp://hdl.handle.net/10016/21155
Does (average) size matter?: Court enforcement, business demography and firm growth
García-Posada, Miguel; Mora Sanguinetti, Juan Sebastián
2015-03-01T00:00:00Z